Cryptosporidium outbreaks in recreational water venues have threatened public health, especially in swimming pools. There is still no reliable treatment technique to remove Cryptosporidium oocysts from swimming pools. The performance of polydiallyldimethylammonium chloride (polyDEDMAC)as coagulant on Cryptosporidium removal from pools was evaluated in this paper. Seeding methods of polyDEDMAC and dosage of polyDEDMAC versus oocysts concentrations were tested. Results indicated oocysts removal efficiency for feeding oocysts and polyDEDMAC simultaneously were more than 99% (2 log), and continuously feeding of polyDEDMAC achieved at least 99% (2 log) removals, compared with removal efficiency was 20% by control experiment without coagulation. All of these experiments indicated that the polyDEDMAC should be fed by pump automatically and continuously in order to maximize oocysts removals. In addition, oocysts concentration impacted the system performance. The higher oocysts concentration consumed more polyDEDMAC. Overall, polyDEDMAC is an effective and promising coagulant to improve oocysts removals from swimming pools.